In the worst outbreak of inter-Palestinian strife since Hamas took over the Gaza Strip last year, Hamas gunmen rounded up hundreds of Fatah activists in Gaza and threw up dozens of checkpoints over the weekend.

The militant Islamist group accused militants from the rival Palestinian leader Mahmoud Abbas's Fatah Party of a bombing that killed five Islamic activists and a young child last Friday.

The attack and retaliation reopened recent wounds in the bitter rivalry just as the sides were mulling a new round of reconciliation talks.

"There is no room now to speak about national reconciliation," says Hamas leader Mahmoud Al-Zahar, who accused Abbas of preferring to discuss US peace talks with Israel rather than the internal Palestinian talks. "[Abbas] is still meeting [Israeli Prime Minister Ehud] Olmert and kissing him.... His preference is the Israel-US side not the Palestinian side."

After returning from the recent Arab summit in Damascus, Abbas declared that he's prepared to discuss restoring relations with Hamas without any preconditions – apparently dropping a demand that the Islamic militants apologize for the takeover and withdraw from the installations they seized when Hamas wrested control of Gaza from Fatah in 2007.

With Palestinians divided under Hamas rule in Gaza and the Palestinian Authority in the West Bank, analysts say that some resolution to the standoff is necessary for there to be any hope implementing any future peace treaty between Israel and the Palestinians in the Gaza Strip.

The internal Palestinian talks are expected to be held in Cairo and focus on an compromise reached between Hamas and Fatah emissaries early this year in Yemen. A date for the talks had never been set.

"Now everything is up in the air," says Mr. Sinora. "What happened in Gaza on Friday is delaying the process of reconciliation, if not undermining it permanently."

A car bomb on Friday ripped apart a car carrying five members of Hamas's military wing and Sireen As Safadi.

Unlike other attacks on Palestinian militants in the Gaza Strip, Israel hasn't been fingered as the culprit. While Hamas put the blame on Fatah, Fatah spokespeople have speculated that it was a result of internal divisions within Hamas.

Earlier on Friday, a bomber blew himself up at a cafe in the center of Gaza City, and an explosion erupted at the residence of a Hamas legislator. Sinora says deposed Fatah strongmen from Gaza like Mohammed Dahlan might prefer continued conflict to a reconciliation that preserves Hamas's dominance in Gaza.

The renewed domestic strife comes amid a several-week calm in hostilities between Israel and Hamas in and around Gaza. Sinora speculated that the new pressure on the Islamic militants from within may prompt it to become less flexible in compromising on a prisoner swap to free Gilad Shalit, the Israeli soldier held in Gaza for more than two years.

The three attacks posed the most brazen challenge yet to Hamas' consolidation of security control over the last 13 months in the Gaza Strip.

The Islamic militants had been credited with restoring a measure of order in the coastal stretch of 1.5 million people after years of chaos and lawlessness under the Fatah-led Palestinian Authority.

At numerous checkpoints around the Gaza Strip, Hamas security forces were pulling over motorists and inspecting car trunks as well as personal backpacks for weapons.

Mr. Sharif predicted that even a formal reconciliation between Hamas and Fatah would not stop ordinary Gazans from settling old scores on their own and suggested that in addition to the politics of the recent attacks, there was the historical factor of clan revenge.

"It is very difficult to put differences aside," he says. "We are Oriental people who have certain traditions that control us. We believe in revenge. Even old people and women who suffered from Hamas will want revenge."

Hamas gunmen also raided the offices of Gaza's regional governorates, confiscating computers, files, and furniture. The regional government institutions had been left under the control of Fatah officials, but Sinora speculated that that arrangement may come to an end.

Indeed, despite the string of bombings on Friday, few interpret it as the harbinger of the loosening of Hamas' grip on the Gaza Strip or of a broad military uprising by Fatah.

"Fatah doesn't have the ranks that can overturn the rule of Hamas there," wrote columnist Avi Issacharoff in Israel's Haaretz daily. "But explosions like those that occurred on Friday are liable to become routine."